Use show-on-hoverclass with dropdown class.

Use dropdownclass for default dropdown.

Just put icon class with i tag.

Use Animate.css classes with data-dropdown-in="fadeIn" data-dropdown-out="fadeOut".

Use Animate.css classes with data-dropdown-in="flipInX" data-dropdown-out="flipOutX".

Use Animate.css classes with data-dropdown-in="flipInY" data-dropdown-out="flipOutY".

Use Animate.css classes with data-dropdown-in="slideInRight" data-dropdown-out="flipOutX".

Use Animate.css classes with data-dropdown-in="bounceIn" data-dropdown-out="bounceOut".

Use Animate.css classes with data-dropdown-in="rollIn" data-dropdown-out="rollOut".